OP, if you are into overclocking and suchlike, I would recommend that you not take a stab at the x2-245e. It is a C3 chip, which is good, but there are (probably) no unlockable variants which is a lot less fun. I picked up an x2-220 recently, unlocked it to three cores and 6mb L3 cache, and run it at 3.6 ghz in that state without any voltage adjustments (well, there's HT/SB voltage bumps, but that's for the motherboard).
If you do your homework, there's great potential for these chips to be a big value-add. Worst-case scenario is that you get stuck with a dual-core CPU which is what you paid for in the first place. As a dual-core, it won't beat a C2D at the same clockspeed sorry to say, though it will keep things fairly close. Unlocked to 3-4 cores, then yeah it'll beat a C2D on anything that can use more than two cores.